1. Field of the Invention
The present invention relates to an Orthogonal Frequency Division Multiple Access (OFDMA), and more particularly to a predefined pattern-based resource partitioning method for partitioning a resource area, a resource partitioning method based on an informed map, and an adaptive resource partitioning method.
2. Discussion of the Related Art
Generally, in order to maximize efficiency of limited radio resources in a broadband communication system, a variety of transmission/reception techniques and usage methods, which are more effective in time, space, and frequency domains, have been proposed in the broadband communication system. Specifically, a multicarrier-based orthogonal frequency division multiplexing (OFDM) scheme reduces the complexity of a reception end under a frequency selective fading environment generated from a broadband channel, performs selective scheduling in a frequency domain using different channel characteristics of subcarriers, such that a spectral efficiency can be maximized. Also, the multicarrier-based OFDM scheme can be extended to an OFDMA scheme by assigning different subcarriers to multiple users, such that many developers are conducting intensive research into this multicarrier-based OFDM scheme to increase the efficiency of radio resources in the frequency domain. The IEEE 802.16-2004 and IEEE 802316e-2005 modified standards (hereinafter referred to as ‘IEEE 802.16’) have been completed as a WirelessMAN-OFDMA standard based on a representative OFDMA scheme.
A logical frame structure of an IEEE 802.16e system includes a preamble, a frame control header (FCH), and a control signal part and data bursts of a DL/UL-MAP, as shown in FIG. 1. Data transmission of each user may be defined by different subcarrier allocation schemes (e.g., PUSC, (O-)FUSC, TUSC, AMC) according to subchannel construction methods. These subcarrier allocation methods can be generally classified into two types, i.e., a distributed method and a localized method. This distributed method allocates subcarriers according to a pattern pre-engaged between a transmitter and a receiver. This localized method allocates an optimized subcarrier area on the basis of feedback information of the receiver at each resource allocation time. The PUSC, (O-)FUSC, or TUSC method corresponds to the distributed method, and the AMC method corresponds to a localized method. In case of the IEEE 802.16e system, a variety of permutation zones may be constructed in a single frame.
FIG. 2 is a conceptual diagram illustrating a method for constructing various zones and transmitting them. Each terminal performs channel estimation, a synchronization process, and a cell ID acquisition process using the preamble, and then receives channel allocation information associated with a DL-MAP and channel code information via the FCH zone. Based on the channel allocation information and the channel code information, regions of each zone and a permutation method of each zone can be allocated via the DL/UL-MAP. If the zone allocation is not newly changed to another, a current zone structure is retrieved, and only one of the above-mentioned different subcarrier allocation methods is selected within a single zone, such that radio resources are allocated to each channel. Therefore, transmission of additional control information for constructing each frame zone is unnecessary.
The partitioning of the distributed resource area and the localized resource area under the IEEE 802.16e frame structure is carried out on the basis of a zone. Only one of two resource allocation methods should be used within only one zone. The above-mentioned method has a limitation in time, such that a method for using areas of two resource allocation methods in different ways is advantageous to the reduction of control signals. However, the above-mentioned method has the limitation in time, such that the allocation of selectable distributed or localized resource areas may be restricted. As a result, a data throughput of the localized resource allocation area may be decreased, or an available diversity for the distributed resource area may also be decreased.
On the other hand, provided that two resource allocation methods can be simultaneously used in only one scheduling area, a location and amount of localizably-allocated resources for each scheduling may be changed to another location and amount, such that the changed location and amount may unavoidably affect the distributedly-allocated resource area. Therefore, in order to allow two resource allocation methods to be used in only one scheduling area, there is needed a method for informing a receiver of a localized allocation area by a current scheduling process every scheduling time, and this method must also inform the receiver of a specific area capable of being used as a distributed resource area.
The above-mentioned information is equal to control information generated in a common control signal (e.g., a preamble or FCH) at each additional scheduling, such that it encounters a waste of radio resources to be allocated to data, resulting in a deterioration of a data transfer rate.